Why are My Douglas-fir Trees Dying?

The Douglas-fir bark beetle is the most destructive beetle attacking Douglas-fir trees in the Seeley/Swan Valley. The potential loss of trees can be considerable and can affect both residential homeowners as well as commercial interests. Outbreaks develop in host trees following stand disturbances such as windthrow, drought, severe defoliation or wildfire, such as the Condon Mountain Fire in 2012. During outbreaks, groups of dead trees may total 100 or more. Yearly mortality in the northern region, which includes Montana, may extend into the millions of board feet.